NZ623437A

NZ623437A - Sulphuric acid production with recycle of desulphurized gas

Info

Publication number: NZ623437A
Application number: NZ623437A
Authority: NZ
Inventors: Mads Lykke
Original assignee: Haldor Topsoe As
Priority date: 2011-09-29
Filing date: 2012-09-27
Publication date: 2016-07-29
Also published as: JP6081466B2; BR112014006769B1; AU2012314458A1; CL2014000701A1; KR20140085416A; MX352948B; UA112662C2; IN2014CN02208A; ES2568635T3; EA201490645A1; CN103826726B; BR112014006769A2; TWI547435B; WO2013044937A1; JP2014534151A; US20140219910A1; KR101998682B1; AU2012314458B2; MX2014003017A; US9045342B2

Abstract

Disclosed is a process for oxidation of sulfur dioxide to sulfur trioxide, for the production of sulfuric acid, and or for desulfurising a process gas, comprising the steps of (a) directing a stream of feed gas, being a process gas, comprising sulfur dioxide and oxygen, to a catalytically active material (b) oxidizing an amount of said sulfur dioxide in said process gas to sulfur trioxide in the presence of at least 0.1% water and the catalytically active material, providing a first oxidized process gas (c) reacting the sulfur trioxide with water in a condensing column, (d) condensing sulfuric acid in a condenser (e) withdrawing a first desulphurized process gas and a first stream of sulphuric acid; and (f) from the desulphurized process gas, withdrawing a recycle stream of desulphurized process gas wherein the recycle stream is added to said stream of feed gas or said first oxidized process gas. Also disclosed is a process plant for desulphurisation of a feed gas said process plant comprising a first bed of catalytically active material, a first condensation unit and a downstream desulphurisation plant, configured for recycling of a stream being withdrawn downstream said first condensation unit and optionally downstream the downstream desulphurisation unit, and being recycled to a process position upstream the first condensation unit, and optionally upstream said first bed of catalytically active material.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A process for oxidation of SO to SO comprising the steps of 5 (a) directing a stream of feed gas, being a process gas, comprising SO and O , to a catalytically active material (b) oxidizing an amount of said SO in said process gas to in the presence of at least 0.1% water and the catalytically 10 active material, providing a first oxidized process gas (c) reacting SO with water in a condensing column, (d) condensing H SO in a condenser (e) withdrawing a first desulphurized process gas 15 and a first stream of sulphuric acid; and (f) from the desulphurized process gas, withdrawing a recycle stream of desulphurized process gas wherein the recycle stream is added to said stream of feed gas or said first oxidized process gas.

2. A process according to claim 1 further comprising the secondary sulphur removal process step of (g) reheating the first desulphurized process gas, (h) oxidizing an amount of the remaining SO in said first 25 desulphurized process gas to SO in the presence of a second catalytically active material providing a second oxidized process gas (i) reacting SO with water, (j) condensing H SO 30 (k) and withdrawing a second desulphurized process gas and a second stream of sulphuric acid

3. A process according to claim 1 or 2 further comprising the process step of (l) heating the recycle stream of desulphurized process gas to a temperature above the dew point of sulphuric acid in 5 the desulphurized flue gas, such as at least 10°C, preferably at least 30°C and even more preferable at least 50°C above the dew point with respect to sulphuric acid in said recycle stream. 10

4. A process according to any one of claims 1 to 3 further comprising one or more secondary sulphur removal process steps taken from the group consisting of (m) removal of sulphuric acid mist by collection of droplets in a mist filter and withdrawal of collected sulphuric acid 15 droplets, (n) removal of sulphuric acid mist by electrostatic precipitation, and removal of precipitated sulphuric acid (o) removal of sulphur oxides by absorption in a scrubber, wherein said scrubber contains an alkaline solution and/or 20 an oxidative solution.

5. A process according to any one of claims 2 to 4, wherein the recycle stream is withdrawn downstream the secondary sulphur removal process step.

6. A process according to any one of claims 2 to 4, wherein the recycle stream is withdrawn upstream the secondary sulphur removal process step. 30

7. A process according to any one of claims 1 to 6, wherein the concentration of SO in the feed gas is above 5 % vol, and below 100% vol, preferably below 30% vol.

8. A process according to any one of claims 1 to 7 in which at least 99% of the sulfur comprised in the feed gas is in oxidised form such as SO or SO or the corresponding acids.

9. A process according to any one of claims 1 to 8 in which less than 50% of said desulphurized process gas is withdrawn as a recycle stream of desulphurized process gas.

10 10. A process according to any one of claims 1 to 9 in which the volumetric concentration of oxygen in said process gas being directed to contact the catalytically active material is at least the same as the volumetric concentration of sulphur dioxide.

11. A process according to any one of claims 1 to 10 in which the temperature of said recycled gas is above 200°C.

12. A process plant for desulphurisation of a feed gas 20 said process plant comprising a first bed of catalytically active material, a first condensation unit and a downstream desulphurisation plant, configured for recycling of a stream being withdrawn downstream said first condensation unit and optionally 25 downstream the downstream desulphurisation unit, and being recycled to a process position upstream the first condensation unit, and optionally upstream said first bed of catalytically active material. 30

13. A process plant according to claim 12, in which said downstream desulphurization unit is taken from the group consisting of (i) a process unit comprising a catalytic material for oxidation of SO to SO and a condenser for condensation of sulphuric acid, (ii) a mist filter for removal of sulphuric acid mist by collection of droplets and withdrawal of collected sulphuric acid droplets, (iii) an electrostatic precipitator, for collection of liquid 5 sulphuric acid from sulphuric acid mist, and (iv) a scrubber for removal of sulphur oxides by absorption in an alkaline solution and/or an oxidative solution.

14. A process plant for desulphurisation of a feed gas 10 according to claim 12 or 13, configured for recycling of a stream being withdrawn downstream said first condensation unit, and upstream the downstream desulphurisation unit.

15. A process plant for production of sulphuric acid 15 comprising a combustion unit for a sulphur rich material upstream a desulphurisation process plant according to claim 12, 13 or 14, in which the stream being recycled is directed to a position upstream or downstream said combustion unit. HALDOR TOPSOE A/S WATERMARK PATENT AND TRADE MARKS ATTORNEYS P38477NZ00